将质量为m的小球在距地面高度为h处抛出,抛出时的速度大小为V0,小球落到地面时的

题型:选择题

问题:

将质量为m的小球在距地面高度为h处抛出,抛出时的速度大小为V0,小球落到地面时的速度大小为2V0,若小球受到的空气阻力不能忽略,则对于小球下落的整个过程,下面说法中正确的是

A.小球克服空气阻力做的功小于 mgh

B.重力对小球做的功等于mgh

C.合外力对小球做的功小于mV02

D.重力势能的减少量等于动能的增加量

考点:动能定理
题型:选择题

关于乳、恒牙区别的说法,错误的是()

A.乳磨牙体积依次减小

B.乳牙冠根分界明显

C.乳牙颈嵴明显突出

D.乳牙体积小,色乳白

E.乳牙根分叉大

题型:选择题

关于传染病流行病学资料,下列不正确的是

A.流行病学资料在诊断中占有重要地位

B.是否患过该病表明有无发病的可能

C.是否在流行地区、流行季节表明有无感染的可能

D.考虑传染病诊断时必须取得有关流行病学资料作参考

E.某些传染病在发病年龄和职业方面有选择性

题型:选择题

Research has shown that music has an important effect on one’s body and psyche (心灵). In fact, there is a growing field of health care known as music therapy(治疗), which uses music to treat diseases. Even hospitals are beginning to use music therapy. This is not surprising, as music affects the body and mind in many powerful ways.

Research has shown that quick music can make a person feel more alert(警觉戒备), while slow music can produce a calm, deep thinking state. Also, research has found that music can change brainwave activity levels. This can help the brain to change speeds more easily on its own as needed, which means that music can bring lasting benefits to your state of mind, even after you’ve stopped listening.

Breathing and heart rates can also be influenced by music. This can mean slower breathing, slower heart rate. This is why music and music therapy can help reduce the damaging effects of long-term stress, greatly promoting (促进) not only relaxation, but health.

Music can also be used to bring about a more positive state of mind by helping to keep worries away. Music has also been found to bring many other benefits, such as lowering blood pressure and reducing the risk of strokes(中风). It is no surprise that so many people are considering music as an important tool to help the body become or stay healthy.

小题1:What can we infer about music therapy(治疗)?

A.It is a type of music.

B.It is a research about music.

C.It is a kind of musical effect on diseases.

D.It is the use of music method to help treat diseases.小题2:According to the second paragraph, we can know that ________.

A.music with different speeds has different effects

B.quick music is not good for one’s health

C.slow music can help one to think more calmly and slowly

D.music will have less benefit after one stops listening小题3:The reason why music can help deal with stress is that ________.

A.it is used by many hospitals

B.it can help change brainwaves

C.it does good to breathing and heart rates

D.it can bring a more positive state of mind小题4:According to the passage, music can help deal with all the following EXCEPT ______.

A.nervousness

B.mind illnesses

C.strokes

D.high blood pressure

题型:选择题

在教师表中统计职称为教授的人数。请对下面的SELECT语句填空:
SELECT 【8】 FROM 教师表 WHERE 职称="教授\

题型:选择题

下列关于无机物描述中正确的是()。

A.不含碳、氢、氧的化合物是无机物

B.一氧化碳是无机物

C.碳酸盐等物质是无机物

D.不含碳元素的物质是无机物

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